I guess that the Linux gurus assume that people want their RAIDs assembled during boot. I don't.
I am able to obtain the following behaviors of MDADM:
a) MDADM auto-assembles during boot. If it can't find a needed physical volume then it marks it as bad/missing and otherwise does things I don't want. I can recover from this condition but it takes some effort. This is the behavior I get if I put the usual ARRAY data in /etc/mdadm.conf.
b) MDADM does not assemble anything during boot, but it also will not let me assemble any raids after boot. This is what happens if I put the following in etc/mdadm.conf:
ARRAY <ignore> UUID=00000000:00000000:00000000:00000000
AUTO -all
I really do not want the behavior of MDADM when it can't find a physical volume. I suppose it is trying to take "reasonable" corrective action - but that is not what I want. If MDADM must do something during boot then I want it to give up if there is any problem whatsoever.
After the systems is up, I use a script that does
madm -A --scan --no-degraded /dev/mdXX --uid YYYYYYYY:YYYYYYYY:YYYYYYYY:YYYYYYYY
for each of my raids. This fails in case (b) above - mdadm complains that the raid device is not in the config file.
How??
How to idle MDADM during boot??
Re: How to idle MDADM during boot??
All you need is "AUTO -all". I suspect your other line that tells it to ignore it is naming the UUID of the array and then you're trying to run a command that wants to auto-assemble that same array and the ignore line tells it never to do so.
I use AUTO -all then have a systemd unit file that runs /usr/sbin/mdadm --assemble /dev/md0 /dev/sda1 /dev/sdb1 (alter to fit your requirements). I also have systemd activating the PV/VG on that md device, mounting the filesystem on /var/lib/mysql then starting mysqld.
I use AUTO -all then have a systemd unit file that runs /usr/sbin/mdadm --assemble /dev/md0 /dev/sda1 /dev/sdb1 (alter to fit your requirements). I also have systemd activating the PV/VG on that md device, mounting the filesystem on /var/lib/mysql then starting mysqld.
The future appears to be RHEL or Debian. I think I'm going Debian.
Info for USB installs on http://wiki.centos.org/HowTos/InstallFromUSBkey
CentOS 5 and 6 are deadest, do not use them.
Use the FAQ Luke
Info for USB installs on http://wiki.centos.org/HowTos/InstallFromUSBkey
CentOS 5 and 6 are deadest, do not use them.
Use the FAQ Luke
Re: How to idle MDADM during boot??
That is exactly what I am trying to do, but it does not work. With just "AUTO -all" in etc/mdadm.conf, when I try to assemble the raids with commands like
mdadm -A --scan --no-degraded /dev/mdXX --uuid YYYYYYYY:YYYYYYYY:YYYYYYYY:YYYYYYYY
I get the error message
mdadm: /dev/mdXX not identified in config file
for each of the mdadm -A commands. The differences between my command and yours are
a) I add the "--no-degraded" command line option
b) I use "--scan" and "-uuid" instead of listing the devices. I don't see how that could work reliably, BTW, since Linux assigns device names more-or-less randomly.
When all else fails read the manual! Having just read the docs for mdadm, I see that "--scan" says "scan config file for missing information". I was thinking it would scan the physical devices. My bad.
However, when I put the ARRAY data for all the raids in /etc/mdadm.conf, then mdadm assembles the arrays during boot. I don't want that!
mdadm -A --scan --no-degraded /dev/mdXX --uuid YYYYYYYY:YYYYYYYY:YYYYYYYY:YYYYYYYY
I get the error message
mdadm: /dev/mdXX not identified in config file
for each of the mdadm -A commands. The differences between my command and yours are
a) I add the "--no-degraded" command line option
b) I use "--scan" and "-uuid" instead of listing the devices. I don't see how that could work reliably, BTW, since Linux assigns device names more-or-less randomly.
When all else fails read the manual! Having just read the docs for mdadm, I see that "--scan" says "scan config file for missing information". I was thinking it would scan the physical devices. My bad.
However, when I put the ARRAY data for all the raids in /etc/mdadm.conf, then mdadm assembles the arrays during boot. I don't want that!